Bullet trap



Jan. 7, 1958 R. M. FERGUSON 2,818,729

' BULLET TRAP Filed July 15; 1955 2 Sheets-Sheet 1 IN VEN TOR.

Jan. 7, 1958 R. M. FERGUSON 2,818,729

' BULLET TRAP Filed July 15 1955 2 Sheets-Sheet 2 byww M 5/ Patented Jan. 7, 1958 (Granted under Title 35, U. S. Code (1952), sec. 26-6) assignor to the United the Secretaryv of The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates generally to a bullet trap, and more particularly to a new and improved apparatus for stopping projectiles shot by guns being tested.

The principal object of this invention is to design a new and improved bullet trap which is compact, safe and economical to manufacture.

A further object of this invention is to provide a bullet trap comprising a closed armored chamber and including an armored block positioned in the path of bullets fired into the armored chamber to confine the high velocity bullets to the chamber.

An additional object of this invention is to construct a bullet trap having a bullet smashing armored block able to oppose the progressive increase in the size of bullet impact indentations in the block by a fusion with fragments of bullets smashed on the block at the point of impact.

Another object of this invention is to provide a bullet trap wherein high velocity bullets are fired into an armored chamber and where the chamber is shaped to let spent bullet fragments gravitate or move out of the chamber;

A still further object of this invention is to provide a bullet trap comprising an armored chamber having spaced parallel end walls wherein high velocity bullets are fired into the chamber through an opening in one of the end walls to hit the other end wall, and including means for preventing ricocheting bullet fragments from returning to the first-mentioned end wall.

Another object of this invention is to provide vent means in the armored chamber for relieving high gas pressures caused by a plurality of high velocity bullets fired into the chamber in rapid succession at relatively close range.

Other objects and many of the attendant advantages of this invention will be readily appreciated as it becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a side elevation of the present invention.

Fig. 2 is a sectional view taken along the sectional line 2-2 of Fig. 1.

Fig. 3 is a side view of one of the baffle plates.

Fig. 4 is a side view of another bafile plate.

Fig. 5 is a side view of the present invention.

Fig. 6 is an enlarged view disclosing the armored block when relatively few bullets have been fired into it, and when the indentation depth caused by the impacts of bullets on the block is still relatively small.

Fig. 7 is an enlarged view disclosing the armored block after many bullets have been fired into it causing the depth of the indentation to become greater and showing the fusion between bullet fragments in the block at the point of impact that opposes the continued increase in the size or depth of the indentation.

Referring now to the drawings, and more particularly to Fig. l, the bullet trap which is adapted for use in high altitude test chambers and which is designated generally at 10 includes an armored chamber 11 composed of octagonal frustum-shaped shell portions 13 and 15 secured together. Each shell portion comprises an end wall and diverging side walls. The end walls are made from standard naval homogeneous armor plate commonly designated as S. T. S. These end walls have an octagonal periphery to conform to the cross-sectional shape of the chamber and have parallel end surfaces perpendicular to the side surfaces at the periphery. One edge of each diverging side wall is secured by welding 45 to each edge of the end wall. The opposite edges of diverging side walls of each shell are welded together at junction 17, see Fig. 1, to form a closed chamber having spaced parallel first and second end walls. The chamber is positioned so the junction of the two shell portions lies in a vertical plane parallel to the end surfaces of the end walls. First end wall 12 of shell portion 13 has a bulletreceiving aperture at its center. Second end -wall 14 of shell portion 15 is a thick massive block of standard naval armor plate and has an impact surface or face 19 disposed substantially perpendicular to the path of the bullet. The armored block is sufiiciently bullet-resistant to prevent standard steel bullets fired into it from penetrating through it and escaping from the chamber. The armored chamber is further provided with a plurality of venting apertures 30 for relieving high gas pressures in the chamber caused by a plurality of high velocity bullets fired into the cham-' her in rapid succession from a position near the bullet receiving aperture in end wall 12. These venting apertures are disposed adjacent junction 17 of the opposed shell portions. An annular chamber 32, see Fig. 5, surrounds these venting apertures in the armored chamber, and is itself provided with a plurality of annularly disposed venting apertures 34. The apertures act to direct gases escaping into the chamber in a direction away from end wall 12 to prevent injury to the gun 50 or to the operator of the gun. An opening 36 for permitting spent bullet fragments to leave the armored chamber is disposed at the lowermost portion of armored chamber 11 at the junction 17 between opposed shell portions 13 and 15.

A plurality of baflles 16, 24, 26 and 28, see Figs. 1, 2, 3 and 4, are secured to the interior walls of the chamber in spaced parallel relationship to prevent bullet fragments from ricocheting back to end wall 12 and injuring the gun 50 or the operator of the gun. The baflle plates are octagonal in shape to conform to the crosssectional shape of the armored chamber and have bulletreceiving openings 20 disposed centrally thereof. In addition, they are positioned so that these openings are in alignment defining a passageway for the bullets. This passageway is substantially perpendicular to impact face 19 of the armored block. The bafiles are further provided with a plurality of venting apertures 1'8 to provide a means for relieving high gas pressures in the armored chamber caused by a plurality of high velocity bullets fired into the chamber in rapid succession. These apertures are in staggered relationship so that the bullet fragments which chance to pass through the venting aperture in one of the bailles cannot directly pass through a venting aperture in the next adjacent baffle. In addition, each battle has a recessed portion 44 disposed at its lowermost edge. These recessed portions are in alignment forming passageways. The passageways are inclined downwardly from each end wall and meet at opening 36. With this arrangement bullets fired into the chamber through the" bullet-receiving'aperture in-end wall 12 are smashed on the end" wall 14 and their fragmentsfallto-the-lOWer surfaces of the chamber andrgravitate through the inclined passageways defined by recesses 44 to opening 36.

From tthere the'fragments fall out of the armored cham ber through exhaust tube 38 and-are defie'ctedby means of deflecting plate 40 outside the apparatus;-

There is an important -.relationship' between the composition of armored block end wall 14and-the bullets'fired into'thechamber; It'will'be appreciated that when a plurality of high velocity bullets are fired into an armored block; no-ma-tter howstrong 'or bullet-resistant the block may-be, an indentation will gradually form under the force ofthe impacts. The rate of growth ofthis inde'ntatidn'dsdirectlyproportionalto the number of bullets fired andthis limits the usefu'l life ofthe smasheror end wall block 14. When-the-armored steel block issulficiently hard, it is'beli-evedthat-the pointed portion-ofthe standard'steel bullets fired into --theblock produces a pressure sufiicient 'to liquefy a portionof the block lat the point of impact whereby fragments of the bullets smashed by the impact become Welded'or fused to the block. The

preferred material of the armored block is made from standard naval homogeneous armorpla-te commercially referred-to-as S.-T. S. having a Brinell numberof-ZSS. However, any steel having a Brinell number around 255 orless would be satisfactory. As seen in Fig. '6,- when the size -of the indentation-46-is still relativelysmall the fusion effect between bullet fragments 48 and the block is also small.- The situation is'difie'rent when the inden-- tation size :hasincreatsed. It is seen in-Fig.7 when the indentation 46 has grown great-er through the increased number of bullets fired into the block, a greater-percentage of -the bullet fragments from thesmashed bullets-come to rest -in-the indentation. Thereafter when bullets are -fired i into this indentation the impact pressureliquefies a pertion'ofthe block at-the point 0f impact causing 'a larger amount of the bullet fragments 'to become weldedto the block: This impact fusing opposes the increased growth ofthe indentation and =greatlyprolongs- :the life of the block. 'Withou-t"this-self-sealing or welding feature the life of a typical "armored block might begood for approximately r1,-2OO rounds butby-selecting-a steel ofproper hardness so =tl1l$- welding; or fusion effect can occur, the

life of a block can be increased-to-morethan 10,000

rounds;

Iri-use the -gunis tested'by fifing aplurality of bulelts irito the biille'treceiving armored block in the armored chamber. armored block caused byihe-success'ive impacts of the bullets increases, more and more bullet fragments come torest in the-indentation, and-under continued pounding by 'the otherincoming bullets, "they become welded to the "block in" the =-in'dentati'on and oppose the continued growth of the indentation. The fragments of thesmashed bullets which do*not adhere *=to "theblo ck are stopped f'by hausted through vents 30 and34.

Thus, it is seen a: simplegcompa'ct and economical 'bu'l- A let' irap has been-wdevised; Obviously manyunrodificationsiaud variationsiof'ithezpresentrinventiomare possible ina-theclight of :the :aboverteachings;, I-t cis, :therefore,rto be understood: thatgtherinventionzmay .be practiced otherwiseethansasr specifically;des-cribedzandsstill, remain-within thescope-of the appendedrclaims I'cla'un .-1. {Asbllllfili traprcomprisingan :armoredechamber, said chamberuhavin'g spaeedparal-lelifirst and-second end walls and; connecting side wwalls, said first endfwal-lhaving- As' the indentation in" end' wall- 14 "in the i bullet-receiving opening therein, said second end wallcoifiprising-an armoredsteelblock having an inner face dis-.

armored block formed fromstanda-rd naval homogeneous armor plate and having a Brinell hardness number of approximately 255 so that the impact pressures between theqarmoreid block-and-thebullets-cause fragments of-the bulletszasmashedJonthe armored block to-fuse t0 the armored block at the point of impact and-'opposenthe progressive increase in the .size of the indentation in the block caused by successive impacts with high velocity bullets.

2. A bullet trapcomprising an armored chamber, said armored chamber having spaced parallel first and'second end walls and connecting side walls, said first end wall having a bullet receiving opening, said second end wall comprisingan armored block having an inner face substantiallyperpendicular to the path of 'the bullet fired into the chamber through the bullet receiving opening in said first end wall; sa'id armored block being sufficiently bullet resistanttto preventthe bullets fired into thechamber from'pen'etrating the ibl'ock and 'escaping fr'om the chamber, aplu'ra'lity of spacedparallel bafiles for preventing the spent bullet-"fra ments from ,ricoc'hetingback to said firstend' Wa'll,".each of said spaced parallel bafiles having a bullet receiving aperture extending the'rethrough, saidbaffles .disposed .in said chamber so the bullet receiving apertures arein' alignment defining a passageway for the bullets substantially perpendicular to the inner face of said armored bloclgyent m'eansgin the armored chamber for relieving'high gas pressures"inlthecharnber caused by a ,plurality of high velocity 'buljlets shot into the chamber in rapid j'succ'es's'ijon, said 'baffie's have venting vent means in ,thearm'ore'dchamber, vent means in said annular chamber adapted to guide'fcscaping gases in a direction away fnomsaid first end wall,

5. A bullet trap comprising ,an' ,armoredf a 3 i armored chamber includingtwo opposed shell portions, each of said shell portionscomprising oneyendwall land diverging side walls,.saidrdivergingside,walls secured at one,edgehtotheperipheryjofzeach endwa'll, the, opposite edgeswof .the diverging. sidewalls ,of each" shell portion secured together to form a closed chamberhaving spaced parallel first and second ,end walls, saidarmoredl chamber disposed. so: the junction of ,the diverg'ii1'g ,side walls of the "opposed .shell- Portions, .lies .in ,a .VerticaYplajne, ,an opening inI-the ,lowermost portion: of th .iarmored cha n; ber at the junction of the shell portions tolet;spent bullet fragments .gravitatesout of 1116 .armored chamber, said firstxend wall having a'bulletrreceiving ,0pening,fsaid@,sec-

ond end wall comprising an armored block, saidbloclc'being sufliciently bullet-resistant to permit -high1.v.elQity bullets fired into the armored chamber through the opening in said .firstrend W al1. and into thearmored block fromzpenetrating through-said armored block an'dtjescaping from the chamber.

6. Theapparatus; setforjthin claim j including', a plurality of spacedparallelibaffles mountedin saijd armored chamber,.,each,ofsaidlbafilesjhaving a recess at one edge, said bafliespositioned so the recesses are in alignment de finingpassageways, said passageways inclined "downward 5 6 1y from the end walls and communicating with the open- References Cited in the file of this patent ing in the lowermost portion of the armored chamber at UNITED STATES PATENTS the junction of the two opposed shell portions whereby spent bullet fragments gravitate to the bottom of the gifg fg aag 5 31 2, chamber move through said passageway to said opening 5 2713262 Websmr Jul}; 1955 and Out Of the armored chamber. 2 772 092 Nikoden Nov 27 195 

